A New Aspect of the Origin of Plasma Turbulence Driven by Field-Aligned Velocity Shear

场对准速度剪切驱动的等离子体湍流起源的新方面

基本信息

批准号：
11480104
负责人：
HATAKEYAMA Rikizo
金额：
$ 9.79万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11480104/
关键词：
Field-Aligned Velocity Shear Low-Frequency Instability Plasma Turbulence

项目摘要

1) A modified plasma-synthesis method is developed in order to actively control an ion flow energy in a magnetic field, where ion and electron emitters of the same diameter are oppositely set at cylindrical machine ends and the ion emitter is concentrically segmented into three sections. The field-aligned ion flows with radially-different energies are generated in a radially-uniform plasma potential when each section of the segmented ion emitter is individually biased at a positive value above the plasma potential.2) This ion drift difference between adjacent layers, or a radial jump of the field-aligned ion flow velocity is found to give rise to several types of low-frequency instabilities.3) One is observed around the radial center where the density profile is almost uniform. This instability is localized around the region of the flow-velocity jump, and the fluctuation amplitude becomes large when the flow-velocity difference between the two electrodes increases. Thus, this instability is considered to be related to the Kelvin-Helmholtz instability to some extent.4) For the larger flow-velocity gradient, another is observed in the region where the density gradient is relatively large. It is found that the frequency of this instability is the sum of the electron-diamagnetic drift frequency and the frequency which is determined by the ion flow-velocity. Thus, this instability appears to be related to the electron-drift and ion-acoustic coupled wave, which has not been argued in the conventional plasma.

1）开发了一种修饰的等离子体合成方法，以便在磁场中积极控制离子流能量，在磁场中，相同直径的离子和电子发射器在圆柱机末端的相反设置，并且将离子发射极浓度分为三个部分。当径向均匀的血浆潜力产生现场对齐的离子流动时，当分段离子发射极的每个部分都以高于血浆电位的正值偏置时，就会产生径向均匀的血浆潜力。2）该离子漂移差异。在径向中心周围观察到密度曲线几乎均匀。这种不稳定性位于流速度跳跃区域周围，当两个电极之间的流速差异时，波动振幅变得很大。因此，这种不稳定性在某种程度上被认为与开尔文 - 螺旋的不稳定性有关。4）对于较大的流速梯度，在密度梯度相对较大的区域中观察到了另一个。发现这种不稳定性的频率是电子 - 磁磁漂移频率的总和和由离子流速度确定的频率。因此，这种不稳定性似乎与电子船只和离子声音耦合波有关，这在常规等离子体中尚未争论。